The prior art has reported surface-normal optical switches using monolithic integration of a heterojunction phototransistor (HPT) with a light-emitting diode (LED); see Sasaki et al., "High Current InGaAsP-InP Phototransistors and Some Monolithic Optical Devices," IEEE Transactions Electron Devices, Vol. ED-29, pages 1382-1388, September 1982; Campbell et al., "InP/InGaAs Heterojunction Phototransistors," IEEE Journal Quantum Electronics, Vol. Q-E-17, pages 264-269, February 1981; and Ogura et al., "Reconfigurable Optical Interconnection Using a Two-Dimensional Vertical to Surface Transmission Electrophotonic Device Array," Applied Physics Letters, Vol. 57, pages 540-542, 1990. There is also prior art disclosing edge-emitting AlGaAs/GaAs lasers; see Schaus et al., "Integrated Lasers/Phototransistor Opto-Electronic Switching Device by Organometallic Vapor Phase Epitaxy," Electronic Letters, Vol. 22, pages 454-456, 1986.
Surface-normal optical switches are based on monolithic integration of an HPT with an LED, sometimes referred to as a vertical-to-surface transmission electrophonetic switch (VTSEP). VTSEP's have been integrated into relatively large (32.times.32) monolithic optically addressable arrays. However, LED-based switches are power inefficient devices having low optical gain and serious optical crosstalk problems. The LED-based structures are inefficient because they require high drive current, have low optical output and have little or no optical gain. In addition, the electroluminescence of light-emitting diodes is not collimated but is Lambertian, giving rise to serious optical crosstalk problems that are intolerable for a densely-packed array in a free-space optical system. Edge-emitting laser-based photothyristors are incompatible with two-dimensional array architectures. Another problem associated with many prior art electro-optical large array devices is that they are adversely affected by electromagnetic interference from various sources.
It is, accordingly, an object of the present invention to provide a new and improved electro-optical device having high efficiency, without problems of optical crosstalk and other effects of electromagnetic interference.
Another object of the invention is to provide a new and improved electro-optical integrated circuit structure for performing binary operations in response to optical signals.
A further object of the invention is to provide a new and improved electro-optical device capable of large-scale integration so that binary optical processing operations can be performed efficiently and with a minimum amount of crosstalk between devices.
An additional object of the invention is to provide a new and improved electro-optical structure, which with slight modification can perform latching, switching and bistable functions.
Still an additional object of the invention is to provide a new and improved electro-optical device incorporating a heterojunction light-emitting device electrically and optically coupled with an optical photothyristor.
Still a further object of the invention is to provide a new and improved electro-optical device wherein feedback between a light-emitting structure and a photothyristor is controlled by implantation of protons into the light-emitting device.